MetaFun: how to check the number of arguments

14 Jan 2019

      Dear all,

In the following sample, it draws squares with label which is given.

I’d like to know how to check the number of elements in the second argument?
If it is 0, then I just draw grids only.

Thank you for reading.
Best regards,

Dalyoung

********
\startbuffer[defs]
def drawGridF (expr nb) (text s) = 
	p := unitsquare scaled wu;
	n:= 0;
	for m = s:
		i:= n mod nb;
		j:= n div nb;
		pic := image (draw p; label(textext(m), center p); );
		draw pic shifted (i*wu, j*wu);
		n:= n+ 1;
	endfor;
enddef;
\stopbuffer

\startbuffer[3x3b]
wu := \MPvar{width};
drawGridF (3)  (1,2,3,0,1, 1,4,5,8);
\stopbuffer

\starttext
\setupMPvariables[width=30pt]
\processMPbuffer[defs,3x3b]
\stoptext
...
2019. 1. 14. 오후 8:00, ntg-context-request@ntg.nl 작성:
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Today's Topics:
1. Re: Manipulating the left blank page when chapter starts on
     the right page (Wolfgang Schuster)
  2. Re: Footnotes in float combinations missing in output
     (Wolfgang Schuster)
  3. Re: Manipulating the left blank page when chapter starts on
     the right page (Jan U. Hasecke)
----------------------------------------------------------------------
Message: 1
Date: Sun, 13 Jan 2019 16:56:40 +0100
From: Wolfgang Schuster 
To: mailing list for ConTeXt users , "Jan U.
  Hasecke" 
Subject: Re: [NTG-context] Manipulating the left blank page when
  chapter starts on the right page
Message-ID: 
Content-Type: text/plain; charset=utf-8; format=flowed
Jan U. Hasecke schrieb am 12.01.19 um 22:08:
...
Hi Aditya,
Am 12.01.19 um 20:11 schrieb Aditya Mahajan:
...
On Sat, 12 Jan 2019, Jan U. Hasecke wrote:
...
Hi all,
in my document \startchapter and \starttitle starts a new chapter on the
right (odd) page. So sometimes, there is a blank even page just before a
new chapter.
I would like to manipulate this blank even page.
There are several things I would like to do, eg. having no headers and
footers, setting the background color to a named color, placing an image
or some graphics on the page.
Is there a way to define such a page, name it and call it in
\startchapter so that it is placed on the left side.
See https://tex.stackexchange.com/q/457428/323
Thanks a lot, but I wasn't looking for a way to just delete page numbers
but to style the empty page in arbitrary ways.
Maybe it is better to do this manually.
I would let chapter open on even pages too and just insert a styled page
by hand.
Here is a example which shows how you can change the background color
of a empty page before the chapter title.
\setuppagenumbering
  [alternative=doublesided]
\startsetups [chapter:before]
  \doifoddpageelse
    {}
    {\pushbackground[page]
     \setupbackgrounds[page][background=color,backgroundcolor=black]
     \page[empty,right]
     \popbackground}
\stopsetups
\setuphead
  [chapter]
  [page=yes,
   before=\directsetup{chapter:before}]
\starttext
\startchapter[title={Knuth}]
\dorecurse{10}{\samplefile{knuth}}
\stopchapter
\startchapter[title={Zapf}]
\dorecurse{10}{\samplefile{zapf}}
\stopchapter
\startchapter[title={Ward}]
\dorecurse{10}{\samplefile{ward}}
\stopchapter
\stoptext
Wolfgang
------------------------------
Message: 2
Date: Sun, 13 Jan 2019 21:06:42 +0100
From: Wolfgang Schuster 
To: mailing list for ConTeXt users , Lars

Subject: Re: [NTG-context] Footnotes in float combinations missing in
  output
Message-ID: 
Content-Type: text/plain; charset=utf-8; format=flowed
Lars schrieb am 09.01.19 um 23:01:
...
Hi there, hi Hans,
I just want to let you know that footnotes insterted in 
float-combinations don't get rendered properly, i. e. only the last 
footnote is placed in the output. MWE:
\starttext
  \startplacefigure[title={OuterCap\footnote{Outer footnote}}]
\startfloatcombination[nx=3]
\placefigure{Fnote1\footnote{Hello}}{\externalfigure[cow][width={.2\textwidth}]}
\placefigure{Fnote2\footnote{small}}{\externalfigure[cow][width={.2\textwidth}]}
\placefigure{Fnote3\footnote{world}}{\externalfigure[cow][width={.2\textwidth}]}
    \stopfloatcombination
\stopplacefigure
\stoptext
Not very nice but the following works. You would have less problems with 
local footnotes which are placed in the float block.
\starttext
\startpostponingnotes
  \startplacefigure[title={...}]
    ...
  \stopplacefigure
\stoppostponingnotes
\stoptext
Wolfgang
------------------------------
Message: 3
Date: Mon, 14 Jan 2019 08:39:45 +0100
From: "Jan U. Hasecke" 
To: Wolfgang Schuster , mailing
  list for ConTeXt users 
Subject: Re: [NTG-context] Manipulating the left blank page when
  chapter starts on the right page
Message-ID: 
Content-Type: text/plain; charset=utf-8
Am 13.01.19 um 16:56 schrieb Wolfgang Schuster:
...
Here is a example which shows how you can change the background color
of a empty page before the chapter title.
\setuppagenumbering
  [alternative=doublesided]
\startsetups [chapter:before]
  \doifoddpageelse
    {}
    {\pushbackground[page]
     \setupbackgrounds[page][background=color,backgroundcolor=black]
     \page[empty,right]
     \popbackground}
\stopsetups
\setuphead
  [chapter]
  [page=yes,
   before=\directsetup{chapter:before}]
\starttext
\startchapter[title={Knuth}]
\dorecurse{10}{\samplefile{knuth}}
\stopchapter
\startchapter[title={Zapf}]
\dorecurse{10}{\samplefile{zapf}}
\stopchapter
\startchapter[title={Ward}]
\dorecurse{10}{\samplefile{ward}}
\stopchapter
\stoptext
Thanks a lot Wolfgang!
This was just the thing I was looking for. These setups seems to be the
golden bullet in ConTeXt but I often have difficulties to understand the
mechanism.
I'll try to wikify this later this week.
The push-pop-background pair is mentionend in x-setups-overview together
with some other push-pop-pairs or push single commands. Are they
documented somewhere?
juh
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Hans Hagen

Jeong Dal

Hans Hagen

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